In the printed wiring board production process, a resin material such as an etching resist, a plating resist, a solder resist, or a prepreg is joined to the surface of a metal layer or a metal trace. In the printed wiring board production process and also in the produced products, high adhesion is required between the metal and the resin. Examples of the known method for improving adhesion between a metal and a resin are the followings: forming fine irregularities on a metal surface using a roughening agent (microetching agent); forming a coating film for improving adhesion to a resin (adhesive layer) on the surface of a metal; forming an adhesive layer on a roughened surface.
For example, Patent Document 1 discloses that an adhesion between the copper circuit and an epoxy resin can be improved when the surface of a copper circuit is subjected to a roughening treatment with an acidic aqueous solution containing copper ion, and then treated with an aqueous solution containing an organic acid, a benzotriazole-based antirust agent, and a silane coupling agent. Patent Document 2 and Patent Document 3 disclose that an adhesion between the metal and a resin can be improved by bringing a solution containing a specific silane compound into contact with the metal surface to form a coating film. Patent Document 4 discloses that an adhesion between the metal and a resin can be improved by applying an antirust agent containing a triazole-based compound, a silane coupling agent, and an organic acid to the copper foil surface.